Carburetor



Jan. 26, 1932.- BOYCE 1,842,469

CARBURETOR Filed Aug. 17, 1929 '2 SheetsSheet 1 FIG. 4

' LEEINARD D BOYCE INVENTOR ATTORNEY.

Jan. 26, 1932. BQYCE 1,842,469

CARBURETOR Filed Aug. 17, 1929 2 Sheets-Sheet 2 LEONARD D BOYCE.

INVENTOR ATTORNEY Patented Jan. 26, 1932 UNITED. STATES PATENT OFFICE LEONARD n. BOYCE, or nArLnwoon, mssounr, ASSIGNOR r cAmsmi cAnsu'nmon CORPORATION, or $1. LOUIS, mssounr, A conronArron or DELAWARE CABIBURETOR Application filed August 17, 1929; Serial Ito. 386,711.

It will be understood that the invention is susceptible .of many modifications, and, accordingly, I do not wish to be limited in my protection, except as set forth in the accompanying claims.

This invention relates to carburetors for internal combustion engines and more particularly to devices for producing a rich mixture of fuel and air for starting purposes. It is well-known by those skilled in the art that a very rich mixture is desirable for starting purposes, partly due to the low engine speed, and partly to the comparatively low temperature prevailing before the engine has had a chance to warm up by operation.

The general class of carburetors to which this engine relates is suction operated spray carburetors. There are two types in this class, one known as air valve and the other as plain tube carburetors. The invention in its broader aspects is applicable to both of these types of carburetors, but I have shown it in connection with a plain tube carburetor, and certain more specific features of the invention are-specially adapted for use with plain tube carburetors. It will be understood by those skilled in the art that the term air valve carburetor implies a suction operated spray carburetor having one or more air passages which are normally closed by a suction operated valve, this valve usually controlling the so-called auxiliary air passage which does not usually enclose the main jet of the carburetor. The term plain tube carburetor will-be understood to imply one in which no suction operated valve is em ployed under normal operating conditions, although such a valve may be used, for operation under abnormal conditions such as starting.

Both air valve and plain tube carburetors of modern construction usually are provided with a main fuel inlet which is surrounded by a comparatively small air inlet passageway, known as the main air inlet, and a somewhat larger auxiliary air inlet. Both main and auxiliary air inlets usually deliver into a main mixing chamber, and the auxiliary air inlet may or may not be provided with an auxiliary fueljet.

An object of this invention is to provide means in a carburetor for restricting the admission of air so that the effect pf the suction produced by the engine will be concentrated on the fuel jet to insure the withfirawal of a suitable-quantity of fuel thererom.

Another object of this invention is to provide a carburetor-having a plurality of air inlets and having simple .and improved means for restricting the admission of air to. said inlets when desired. Other objects of this invention will appear from the following description and the accompanying draw-" ings, referring to which Figure 1 shows a sectional elevation of a carburetor constructed according to my invention.

'Figure 2 shows a sectional elevation, the same as Figure 1, except that the control valves are in a ditlerent operating position.

Figure 3 is a detail view of the primary choking device.

Figure 4 is an end view choking device. 15 Figure 5 is an elevation of the carburetor showing the connections between the throttle and the choke, with parts broken away for clearer illustration of others.

The reference numeral 1 indicates a casting forming the main body of the carburetor. which casting is provided with a seat 2 to which an outlet member 3 is attached bysu'itable'means such as bolts 4;. The flange 5 is provided by means of which the carburetor is attached .in conventional manner to the intake manifold of an internal combustion engine. The outlet member 3 forms a passageway 6 containing a butterfly throttle 7 and a restricted portion or a venturi 8. The in in body member 1 forms an air chamber 9 which is adapted to receive air from the air horn 10, and is provided with a seat 11 against which a cup-shaped fuel bowl 12 is pressed by means of the screw 13 which extends through an opening in the .bottom of the cup and which is thre ded to the main body member at 14. a

The fuel is supplied to the bowl by conof the primary ventional means (not shown), and the level with a suitable flange 22 is threaded into the main body member, as indicated. The bore .23 of the standpipe surrounds the nozzle 20 and is provided with a restrictedportion or venturi 24, the throat of which is near the upper part of the nozzle 20. In this embodiment of the invention, a pair of oppositely disposed rectangular ports 31 are formed in the wall of the standpipe just, below the venturi. The choke tube or standpipe extends upwardly to terminate near the throat of the main venturi 8. The upper part of the choke tube is not as large as the throat of the venturi 8, and an annular air passage 25 is left for the admission of auxiliary air. This opening 25 may be closed when desired by means of a choke valve 26. This choke is provided with a collar 27 and is operated by a yoke 28 fixed to the shaft 29, which shaft is operated by manual means, comprising a lever 70. In order to produce a more efiicient vaporizing effect, I provide one or more small openings 35. These openings are above the top of the choke cone 26 when the choke is open, as shown in Figure 1, and the openings 35 are closed by the choke when it is in closed position, as shown in Figure 2.

The choke operating shaft 29 is connected by a link 57 to the member 58 which is rotatably mounted on the shaft 30. An abutment 59 carried by the member 58 is adapted, tocontact with ascrew 60. This screw is carried by the operating lever 61 on the throttle shaft 30 in such a manner that when the choke 26 is closed, the throttle will be forced at least partially open.

The position of the throttle and choke levers shown in full lines in Figure 5 indicates the open position of thechoke and closed position of the throttle as shown in Figure 1. The dotted lines in Figure 5 indicate the closed position of the choke and slightly open position of the throttle as indicated in Figure 2.

The restriction provided by the closure of the passageway 25 by the choke 26 might be suflicient for starting, provided that the engine is not so stifi'. due to low temperature conditions, that the starter can not turn it over rapidly. But the slow rotation of thestarter, such as occurs in cold weather when the'oil is thick and heavy produces very little suction, and this is relieved to such an ex-= tent by air entering through the port 31 that suitable quantities of fuel. are not drawn 4 from the nozzle 20. r

I have provided a primary choke means for restricting this air passage, comprising a member 32 passing through the choke valve 26 and bent into a loop around the nozzle 20, as shown. This member, which in the present instance is a wire, is movable up and down in the slots 31 so that it may be made to contact with the bottom of the venturi 24, thus restricting the admission of air through that passageway. It will be understood that the air is not entirely out off, but that a small leakage will occur so that at least some air may enter the mixing chamber, even when both the choke and the wire 32 are in closed position. The wire 32 is slidably fitted to a longitudinal channel 91 in the choke, as indic'ated, so as to be operated thereby. The upper end of the wire 32 is bent over at 33 to form an abutment in the path of the choke 26 in its upward movement, and is also bent outwardly at 43 below the choke valve 26 to form an abutment in the path of the choke in its downward movement.

It will be seen that the above structure produces a lost motion movement whereby the primary choke 32 is operated by the secondary choke 26.

When the choke is in open position, as shown in Figure 1, the wire 32 is retained at the lower part of the slot 31 so that it does not interfere with the admission of air to the venturi 24, but when the choke is in its upper or closed osition, as shown in Figure 2, the upper end of the choke comes in contact with the bent portion 33 of the wire 32, holding the lower bent portion 34 of the wire 32 in contact with the lower end of the venturi 24, thereb greatly restricting the an passageway. t this time the air ports 35 are closed by the body of the choke 26 so that the only air which can enter the main mixing chamber 36 is that which leaks through past the bent portion 34 of the wire 32 and that which can bleed in through the small bleed ports 37 and 38.

The throttle valve 7 being slightly open for starting purposes, the suction developed by the engine will not be relieved by large quantities of air entering the carburetor, but will be concentrated on the jet nozzle 20, thus drawing in a very rich mixture of fuel and air.

The operation of the device is as follows:

When it is desired to start the motor, the shaft 29 is operated to close the choke 26 and the passageway between the nozzle 20 and the throat of the venturi 24. The closing movement of the choke also forces the throttle to slightly-open position as shown in Figure 2.

When the engine-is operated by the starting means, air enters the air horn 10 and flows through the bleed ports 37 and 38 and of the venturi 24. Fuel is drawn from the with air from the port 37 which enters the nozzle through the openings 39, and an emulsion is formed which passes from the nozzle 20 at the throat of the Venturi 24, at which point it is further mixed with air entering at that point and is carried through the main mixing chamber'36 to the passageway 6 and from there into the engine. A small amount of air entering the bleed port 38, and that entering at the adjustable idling port 40, mixed with fuel drawn up through the idling duct 41, are discharged at the port 42 and mixed with the mixture coming up through the standpipe and the main venturi.

The mixture thus formed is suitable for starting the engine, even under the coldest conditions. After the engine is started, the,

choke 26 is slightly opened, permitting air to enter through the auxiliary passage 25 and also completely opening the ports 31 and the carburetor continues to operate in the usual manner.

It will be understood that after engine has been run for a short time with the choke 26 slightly open, this choke is then fully open so that a large amount of air may enter to form the economical mixture desired for ordinary running conditions.

I claim: 7

1. In a carburetor, means forming a main mixing chamber, primary and auxiliary air inlets for said chamber, said primary air inlet comprising a choke tube having a port in the side thereof, a fuel nozzle extending into said choke tube, said nozzle being of smaller diameter than the inside of said tube, a valve controlling said secondary air inlet, means for controlling said valve, a wire bent around said nozzle and slidable thereon to restrict the passageway between said nozzle and said tube, operating means for said bent wire, said means comprising an abutment adapted to obstruct the path of a port operated by said secondary valve,.and operating means whereby the primary air passageway may be restricted by operating the valve for the secondary air passage.

2. In a carburetor, a main mixing chamber, a choke tube discharging into said chamber, an auxiliary air inlet for said chamber, a fuel nozzle discharging into said choke tube, an annular main air inlet for said choke tube surrounding said nozzle, a valve for controlling said secondary airinlet, a valve slidable on said nozzle for controlling said primary air inlet, interconnected means for operating said valves, and means for bleeding small quantities of air into said nozzle irrespective of the position of said valves.

3. In a carburetor, means forming a mix ing chamber, a choke tube. discharging into said mixing chamber, a fuel nozzle discharging into said choke tube, means comprising an opening of constant size regardless of suction for bleeding air into said nozzle at a. point below the fuel level, a primary air inlet for said choke tube, a secondary air inlet for said mixing chamber, and an outlet valve for said mixing chamber, means for restricting said secondary inlet, and means in said choke tube for restricting said primary inlet.

4. In a plain tube carburetor, means forming a mixing chamber, a choke tube discharging into said mixing chamber,,an air bled fuel nozzle discharging into said choke tube, a primary air inlet for said. choke tube, a secondary air inlet for said mixing chamber, and an outlet valve for said mixing chamber, means for restricting said secondary inlet, means in said choke tube for restricting said primary inlet, and means for interconnecting said restricting means.

5. In a plain tube carburetor, means forming a mixing chamber, a choke tube discharging into said mixing chamber, an air bled fuel nozzle discharging into said choke tube, a primary air inlet for said choke tube, a secondary air inlet for said mixing chamber, and an outlet valve for said mixing chamber, positive means for restricting said secondary inlet, means insaid choke tube for restricting said primary inlet, and means for interconnecting said outlet valve and said inlet restricting means.

6. In a carburetor, means forming a mixing chamber, a choke tube discharging into said mixing chamber, a primary air inlet for said choke tube, a secondary air inlet for said mixing chamber, a valve slidable in said choke tube for controlling said secondary air inlet, a longitudinal member extending through a part of said valve, means controlled by said longitudinal member for controlling said pri mary air inlet, and spaced abutments on said longitudinal member forming a lost motion connection, whereby said member may be actuated by said valve.

7. In a carburetor, a constant level fuel supply chamber, means forming a mixing chamber, a choke tube discharging into said mixing chamber, a primary air inlet for said choke tube, a secondary air. inlet for said mixing chamber, means for positively restric ting said inlets, said means being interconnected and adapted to be operated by a single operating member, and means for introducing air for forming a starting mixture, comprising an air inlet normally below the fuel level in said constant level chamber.

In testimony whereof, I aflix my signature I 

